Gastrointestinal neuroendocrine tumors: a role for targeted therapies?

Traditional therapies have offered patients with advanced gastrointestinal neuroendocrine tumors limited benefit. Selected patients with hepatic metastases may benefit from surgical debulking, embolization, or other ablative therapies. While somatostatin analogs are highly effective in controlling symptoms of hormonal secretion, they are only rarely associated with tumor regression. The clinical benefit associated with the administration of systemic agents such as interferon-alpha or cytotoxic chemotherapy is less clear, and the widespread use of such regimens has been limited by their relatively modest anti-tumor activity, as well as concerns regarding their potential toxicity. The mixed clinical results seen with these agents in neuroendocrine tumors have led to great interest in the development of novel treatment approaches for patients with advanced disease. Recent clinical studies of novel agents, particularly those targeting the vascular endothelial growth factor pathway and mammalian target of rapamycin, have demonstrated promising activity in patients with advanced neuroendocrine tumors. Ongoing randomized studies should help better define the role these and other targeted agents will play in the future treatment of patients with this disease.